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SUMMARY:Testing the gravitational sector with black hole perturbations - R
 iccardo Penco\, Carnegie Mellon University
DTSTART:20201104T141500Z
DTEND:20201104T151500Z
UID:TALK153049@talks.cam.ac.uk
CONTACT:Scott Melville
DESCRIPTION:Gravitational wave observations allow us to probe directly the
  nature of black holes. This provides us with an unprecedented opportunity
  to test the gravitational sector. I will argue that effective field theor
 y (EFT) techniques provide a natural framework to constrain possible depar
 tures from General Relativity (GR) in a model independent way.\n\nTo illus
 trate this point\, in this talk I will focus on a particularly striking de
 parture from the black hole solutions of GR\, namely the existence of scal
 ar hair (i.e. one or more scalar fields with a non-trivial radial profile)
 . I will introduce an EFT for perturbations around spherically symmetric s
 pacetimes with a scalar hair\, and then discuss a couple of applications i
 n different regimes.\n\nFirst\, I will apply this formalism to study quasi
 -normal modes (QNM) of static black holes with a scalar hair. Assuming tha
 t the deviation of the background from Schwarzschild is small\, I will use
  a WKB approximation to introduce the notion of "light ring expansion" -- 
 an approximation analogous to the slow-roll expansion used for inflation -
 - and provide a model independent parametrization of the QNM spectrum. Sec
 ond\, if time allows it\, I will use this EFT to calculate the power emitt
 ed by an extreme mass-ratio binary inspiral in the post-Newtonian limit.
LOCATION:ONLINE - Details to be sent by email
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